Fluid system for an underwater ground mine



Oct. 13, 1964 R. H. PARK 3,152,546

FLUID SYSTEM FOR AN UNDERWATER GROUND MINE Filed sept. 15, 194e s sheets-sheet s :L es

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gmc/Wto@ Oct. 13, 1964 R. H. PARK 3,152,546

FLUID SYSTEM FOR AN UNDERWATER GROUND MINE Filed Sept. 13, 1946 3 Sheets-Sheet 2 Oct. 13, 1964 R. H. PARK FLUID SYSTEM FOR AN UNDERWATER GROUND MINE Filed sept. 13, 1946 5 Sheets-Sheet 1 Sme/w10@ RJ11-ark United States Patent O 3,152,546 FLUID SYSTEM EUR AN UNDERWATER GRUUND MINE y A, Robert H. Park, 163 Clmenront Road, Bernardsville, NJ. Fiied Sept. 13, 19d-6, Ser. No. 696,963 9 Claims. (Cl. 102-18) (Granted under Titie 35, U.S. Code (1952), see. 266) This invention pertains to a pressure responsive firing mechanism employing a fluid system or use in combination with an underwater ground mine and which is adapted to operate an electroresponsive detonating device for eX- ploding the mine in response to a negative pressure wave set up within the water by a vessel passing over the immediate area in which the mine is planted, and more particularly to a system of this character in which a portion of the fluid employed in the system is supplied and filtered from the surrounding water.

In devices of this character heretofore devised it has been found that when the mine is planted within a body of water in which the bed of the water is composed of soft material such as mud or silt, the mine sinks and comes to rest beneath the surface of the bed and the mud or silt of which the bed is composed may enter the fluid system of the mine in suliicient quantity to interfere with the operation of the pressure responsive mechanism and thereby cause the mine to be unresponsive to the pressure signature of a passing vessel and fail to explode beneath the vessel.

In accordance with the present invention this diiiculty has been overcome by the provision of a filter device disposed in this fluid system between the liuid actuated'ring mechanism and the surrounding water whereby the system may employ the Water as luid for operating the ring control mechanism in response to the pressure signature of a passing vessel without any possibility of the system becoming deranged or rendered inoperative by reason of foreign matter admitted thereto from the surrounding rnedium.

It is an object of this invention to provide a iuid system for use in combination with an underwater ground mine in which at least a portion of the system is adapted to be illed from the water within which the mine is launched, the system having provided therein a iilter' so arranged as to iilter the water of solid matter before it is allowed to ow into the system.

Another object of the present invention is to provide a new and improved pressure responsive Iiring mechanism for use with an underwater ground mine, the firing mechanism including a fluid system in which at least a portion of the liuid used therein is supplied from the surrounding water after the mine has been launched, the fiuid system including a iilterY arranged thereinv andi adapted to iilter solid matter from the water'before the water enters the system.

Another object ofn this invention isL to provide a new and improved pressure responsive fluid system adapted to hre an underwater ground mine in' response to a negative pressure wave applied thereto by the movement of a vessel over the mine, one portion of the fluid system being filled with oil while the other portion of the system is adapted to be iilled with Water' received through a filling duct after the water has been filtered of solid matter by a ilter device arranged in the duct.

A further object of the present invention is to provide a pressure responsive iiuid system for use with an underwater ground mine, wherein a portion of the iiuid in the system is filtered and supplied from the surrounding water by way of a filling duct, the system including a resilient diaphragm in communication with the surrounding water whereby changes in the pressure of the sur- 3,152,545 Patented Oct. 13, 1964 lCe rounding water are rapidly communicated to the fluid in the system by the diaphragm.

A still further object is to provide a fluid illed system for an underwater mine adapted to be red in response to apre'determined negative pressureV change in the surrounding water applied to a liexible diaphragm connected to the system, in which a substantial pressure bias is prevented from being continuouslyv applied to the diaphragm by a duct connecting the system with the surrounding water, and in which means are provided for iiltering the water tiowing into the system inwardly through the duct.

Other objects, advantages, and improvements will more clearly appear as the description proceeds, reference being now made to the accompanying drawings of which:

FIG. 1 is a view in schematic form of the pressure responsive system of the present invention and including the firing mechanism control element employed therewith;

FIG. 2 is a sectional view of the system of FIG. 1 showing a suitable arrangement of the firing contacts and control mechanism therefor;

FIG. 3 is a top plan view of the device assembled to the mine casing;

FIG. 4 is a View taken alongthe line li-d'of FIG. 2;

FlG. 5 is a schematic diagram of a tiring circuit suitable ior use with the present invention.

FIG. 6 is a view partly in section of an alternative iilter arrangement suitable for use with the present invention; and

FG. 7 is a graph of the pressure signature of a moving vessel.

Referring now to the drawings on which like numerals ofv reference are employed to designate like parts throughout the several views and more particularly to FIG. 1 thereof, there is shown therein a fluid system adapted to be lilled from the surrounding water as the mine is planted. This water filled portion of the system comprises two compartments 19 and 11' formed by the housings 12 and 13' respectively. The housing 12 is in the form of a concave depression within the plate member 14 the opening thus formed being suitably closed by a resilient diaphragm member 15 composed of material suitable' for the purpose such, for example, as rubber or any of the synthetic varieties thereof and arranged so that the' outer surface thereof is continually exposed to the surrounding water within which the mine is planted. The outer surface of the diapl:u'a,f:,rn`v is shielded from possible damage by the perforatedv plate or cover 16 concavely formed with respect to the diaphragm to permit a considerable degree of free movement of this member is an outwardly direction. Any suitable means such as the bolts 17 may be employed for securing the cover, diaphragm and housing 12 to the mine casing 18. The arrangement illustrated on FIG. 1V provides that the diaphragm be disposed between the two members 12 and 16 with all three members clamped to the casing by bolts 17. The gasket 19 provides a watertight seal between the housing 12 and the mine casing 1S. Centrally arranged within the housing 13' is the eXpandi-ble elementV 21 that is instrumental in tiring the mine when properly actuated by a predetermined iiow of iiuid within the system, as will be more clearly apparent as the description proceeds.

Fluidly connecting the two compartments 1i) and 11 is a duct 22 having a constricted opening 23 therein of a diameter adapted to reduce to a predetermined degree the ilow of liuid from one of said compartments to the other. The water that provides the pressure communicating medium within the system is supplied through a liller duct 24 that connects with the water outside of the mine through the filter assembly 25 It will be understood that this lter may be of any design, structure or material suitable for the purpose. The filler duct 24 connects with l? the system in such a manner that water entering thereby will have to pass through a portion of the restricting opening 23 within the duct 22 before entering the compartment 11 for effecting the element 2l. This ow restricting duct element 23 controls the rate of change in the volume of fluid within the compartment 11 in response to sudden changes in pressure in the surrounding water.

For a better understanding of the device, reference is made tio FIG. 2 on which is shown in greater detail a preferred arrangement of the uid system and the firing contacts controlled thereby. In this arrangement the compartment 1G comprises a recess formed within the mounting plate 26 over which is arranged the resilient diaphragm i suitably protected by the convex perforated shield member 16. The shield and diaphragm are secured to the mounting plate by a plurality of bolts 27 circularly arranged around the peripheral flange of the shield member substantially as shown in FIGS. 2 and 3. The mounting plate 26 is secured to the mine casing 18 by a plurality of bolts 23, a gasket 29 composed of material suitable for the purpose being arranged therebetween to provide a watertight joint. Suitably secured to the lower surface of the mounting plate 26 by means of bolts 32 are the cup-like housings 33 and 34 respectively. Sealing connections are maintained between these members by means of the gaskets 35 and 36 arranged therebetween.

Centrally positioned within the upper housing 33 is the expansible bellows 2l sealed at the lower and thereof to an internal ange 37 formed on the housing thereby to divide the housing into two compartments, 11 and 38, the outer compartment 1l being adapted to be filled with water received through a port 39 centrally arranged within the plate 26, Whereas the space within the bellows is filled with oil. The upper portion of the bellows 2l is adapted to be brought into engagement With a plurality of protuberances il formed on the plate 26 when the bellows is fully expanded. An annular plate 42. is secured to the fiange 37 of the housing 33.

Centrally formed within the plate 42 is a cup or guide member 43 within which is slidably arranged a piston 44 retained therein by the plate 45, the plate being suitably secured to the partition by means of screws 46 airanged around the periphery thereof, FIGS. 2 and 4. The piston is yieldably retained in its extended or normal position by a spring 47 arranged between the base of the piston and an internal ange i3 formed on the guide member 43, the base of the piston being in communication with the chamber 38 by an aperture 51 formed in the guide member 43.

Mounted on the retaining plate and insulated therefrom is a spring switch member 53 provided with a contact 54 adapted to engage a fixed contact 55 in response to a predetermined degree of movement of the piston 44 from an initial positon thereof as will more clearly appear as the description proceeds. An external electrical connection being established to the switch member 53 by conductor 5i). The terminal connection 60 being electrically insulated from the housing 34 by Washer 71. This member 53 is normally held in an open circuit position with respect to the fixed contact 55 by means of an extension 56 composed of insulating material and formed on the piston 44.

The housing 34 is provided with a centrally arranged aperture 57 about which is arranged an expansible bellows 53 hermetically sealed to the housing 34 as at 59. The bellows 53 is yieldably urged inward by a resilient member 61 retained in the actuated position by an annular plate 62 secured to the housing 34 by screws 63. The housing 34 is provided with a filler hole 64 through which is supplied a quantity of oil sufiicient to lill the chamber 65 within the housing 34 and the chamber 38 within the housing 33. Communication between the chambers 65 and 38 being established by a bleeder port 66 formed therebetween. After the housings have been filled with oil the filler hole 64 is sealed by a plug 67.

From the foregoing it will be clearly apparent that the chambers 65 and 3S are filled with oil prior to the launching of the mine and the chambers 10 and 11 are filled with water admitted thereto by the duct 24 after being filtered by the filter 25.

On FIG. 6 of the drawing is shown a variation of the filtering arrangement employed with the present invention wherein the filter '75 thereof is preferably formed as a ring and positioned around a flexible diaphragm 76. The filtering device is suitably housed Within an annular depression 77 formed Within the under face of the cover plate '73. This cover plate 78 is concavely formed with respect to the free movable portion of the diaphragm 76 to permit movement of the diaphragm in an outward direction in response to a decrease in pressure applied to the outer surface thereof as the result of wave action or the passage of a moving vessel above the mine. The perforations '79 in the cover plate operate to admit water to the outer surface of the diaphragm while the perforations 8l oircumferentially arranged Within the upper port-ion of the filter housing 77 admit water into the compartment 10. Water entering the housing through the perforations S1 passes lter 75 and thence into the compartment 10 through openings 33 circularly arranged about a depression 84- Within the supporting plate 85. This depression allows free movement of the diaphragm in an inward direction in response to an increase in pressure applied to the outer surface thereof. The perforations 86 within the depression 84- admit the water, entering the compartment through the filter system, to pass on to the under side of the diaphragm 76. The filter 75 is preferably relieved as at 3f) and 82 adjacent the perforations 83 and 81 respectively. The diaphragm includes a circular extending surface 83 which forms a sealing gasket between the cover i8 and the supporting plate as these two members are drawn together at assembly by the tightening of bolts 89. Within this extended portion of the diaphragm are arranged a plurality of apertures 74 in substantial alignment with the openings 83. The diaphragm, plate and filter assembly is secured to the mounting element 92 by bolts 91 circumferentially arranged around the outer flange thereof. The housing 34 is attached to the mounting 92 by bolts 32 and encloses the same firing mechanism as FIG. 2.

On FIG. 7 of the drawings is shown the pressure signature lili) of a moving vessel 9th at a fixed point of reference Within the water at a predetermined depth such, for example, as 40 feet. As the vessel 90 moves across the reference point the pressure at 93 is increased and thereafter rapidly decreased to a value less than the static head of the water 102 as indicated at 94 and 95. It will be noted that this negative pressure condition is maintained for a period of time substantially equal to the time of passage of the vessel past the point of reference and considerably in excess of the negative pressure signature received by the system from a wave.

The operation of the device of FIG. 2 will now be described. Let it be assumed, for example, that a mine including this mechanism has been launched within a body of Water. As it sinks therein the diaphragm 15 of the device is gradually forced inwardly by the increasing hydrostatic pressure applied externally thereto. Simultaneously with the sinking of the mine water begins to flow into the compar-tments 10 and 11 through the filter 25 and duct 24. This inflow of water into the system continues until the pressure on both sides of the diaphragm is equal to the pressure of the surrounding water. This equilibrium of pressure allows the diaphragm 15 to assume its normal unbiased position regardless of the depth at which the mine is planted. Assuming further lthat the mine comes to rest upon a bottom composed of mud or silt, the filter 25 operates to strain the water passing therethrough of such extraneous matter as would otherwise damage or render the system inoperative if admitted thereto. After the fiuid within the system has once reached a state of equilibrium, any subsequent change in pressure of the surrounding water caused either by waves, tides or a moving vessel will set the fiuid therein flowing again, this time in the direction of the volume under the lesser pressure.

The hydrostatic pressure of the surrounding water when applied to the fluid within the system, compresses the bellows 21 inwardly thereby forcing a portion of the oil therein out through -the bleeder port 66 into the chamber 65 and causing the bellows 58 to be compressed inwardly against the resisting action of the spring 61. This flow of fluid will continue in an inward direction until .the spring force against the inner surface of the bellows is equal to that of the hydrostatic pressure applied to the outer surface thereof. When the forces are equalized throughout the sys-tem, the fiow of fluid therein ceases, leaving the surfaces of the bellows 21 and 58, for the purpose of description, in the position indicated by the dash lines 68 and 69 respectively.

Let it now be assumed that the mine system has reached a state of equilibrium and that a vessel traveling at -a speed sufficient to operate the device approaches the mine. The positive pressure wave that precedes a moving vessel, as indicated by 93, FIG. 7, momentarily forces the diaphragm 15 inwardly to start the fiuid within the system flowing in the direction of the back volume or compartment 65 thereby to compress the spring actuated bellows 58. As the bow of the vessel moves over the mine there is a sudden decrease in pressure as indicated by 94 of the graph, which is immediately communicated through the fluid in the system to the surface of the bellows 58 that responds by expanding or moving outwardly under the action of the spring 61 adjusting itself to this lesser pressure now acting thereon. The rate at which this bellows 58 is permitted to expand is controlled by the size of the restricting orice 39. This orifice 39 is of `such a diameter as to control the flow of water from the compartment 11 which must be displaced into the outer compartment in order that oil can be forced -in-to the compartment 38 by the spring actuated bellows 58. The size of this restricting orifice 39 bears a predetermined ratio 4to the bleeder por-t 66 such, for example, a ratio of four times the size of the bleeder port 66 and therefore to compensate for the more rapid displacement of uid from the compartment 11 the piston member 44 is gradually forced inwardly against the spring 47. If this decrease in pressure is sufiiciently prolonged, as in the assumed caseV of a vessel moving over the mine, the piston member will be forced inwardly for a distance sufficient to cause the firing contacts 54 and 55 to close thereby firing the mine.

The orifice 39 is employed to retard the flow of water between the compartments 10 and 11 suiciently to prevent the closing of the firing contacts 54 and 55 as the result of wave action. It is understood that in response to this rhythmic change in pressure due to waves, the piston member 44 may be caused to work back land forth to some degree within the guide member 43 but will not be caused to move inwardly to the extent of closing the contacts 54 and 55 until the sudden decrease in pressure is immediately followed by a continued negative pressure in excess of a predetermined period of time.

The purpose of the bleeder port 66 is to compensate for gradual changes in pressure caused by tides by allowing a gradual exchange of fluid within the system without operating the switch actuating piston member 44 to a firing position.

In the firing circuit shown in FIG. 5 the electroresponsive detonator 96 is positioned to explode the charge 97 when energized by the battery 98 the firing circuit including the firing contacts 54 and 55 and a series connected arming switch 99. The arming switch 99 is of any type suitable for the purpose adapted to close its contacts in predetermined time delayed relation with respect to the planting of the mine such, for example, as the illustrated hydrostat 101 which is retained in :an initial unoperated condition until a soluble washer (not shown) has dissolved. This switch mechanism is well known in the art and forms no part of the present invention. l

The firing circuit of FIG. 5 represents only one form of ring arrangement suitable for use with the present invention yand it will be readily understood that this device may be successfully incorporated in any number of diderent firing circuits or used in combination with any suitable apparatus in order to obtain the desired result.

The operation of the device of FIG. 6 is generally similar to the operation of the device of FIG. 2 and willbe clearly understood by a consideration of the foregoing description of the operation in the Iassumedl example.

It is to be further understood that various arrangements and construction of the par-ts may be resorted to without departing from the spirit or scope of the invention.

The invention herein described and claimed may be manufactured and used-by or for the Government of the United States of America for governmental purposes without the payment of :any royalties thereon or therefor.

What is claimed as new and desired `to be secured by Letters Pat-ent of the United States is:

1. In an underwater ground mine, the combination of a casing, an explosive charge arranged within said casing, an electroresponsive detonator adapted to explode said charge, a circuit including means for firing said detonator, at least one switch for controlling said circuit, a movable member for controlling said switch, a fluid system in which the fiuid flow therein is adapted to control the movement of said movable member in response to changes in hydrostatic pressure applied to said fluid, a duct for filling at least a portion of said system from the water i'n which the mine is planted, water filtering means arranged in said duct for excluding foreign matter from'said fiuid system, and a diaphragm interposed between the said water filled portion of said system and the surrounding water, said diaphragm being adapted to transmit rapid changes in hydrostatic pressure of the surrounding water to the fluid in said system.

2. In an underwater ground mine, the combination of an explosive charge, an electroresponsive detonator adapted to explode said charge when energized, an electrical circuit for controlling the energization of said detonator, a normally open switch included in said circuit, a fluid system having at least a portion thereof adapted to be filled from the surrounding water when the mine is launched, a filling duct for admittingwater to the water filled portion of said system, a filter arranged within said duct and adapted to filter the water entering therein, switch actuating means disposed within said system and adapted to be moved responsive to a flow of the fiuid therein sufficiently to close the switch and thereby energize said detonator when the fiuid within the system flows for a predetermined period of time in response to a predetermined change in hydrostatic pressure applied thereto, and means in communication with the surrounding water for applying said predetermined change in pressure to said fluid system.

3. In an underwater ground mine, the combination of a fluid system having at least a portion of fluid therein to be supplied from the surrounding water after the mine is launched, a filling duct adapted to admit water to said fluid system, a filter arranged in said filling duct and adapted to filter the water entering therein, a diaphragm interposed between said water filled portion of said system and the surrounding water, said diaphragm being adapted to transmit rapid changes in hydrostatic pressure of the surounding water to the fiuid in said system thereby to cause the fluid therein to flow responsive to said changes in pressure, a mine firing mechanism, and a member movable in response to said fiuid fiow for actuating said firing mechanism upon a predetermined degree of movement of said movable member.

4. In an underwater ground mine, the combination of a casing, an explosive charge arranged within said casing, an electroresponsive detonator adapted when energized to fire said charge, a circuit including means for energizing said detonator, at least one switch for controlling said circuit, a movable member adapted to control said switch in response to a hydrostatic pressure differential applied to said movable member, means for applying said pressure differential to said movable member, said last named means including a fluid system having at least a portion of the fluid therein supplied from the water in which the mine is launched, a filling duct adapted to admit water to said system, filtering means connected in said duct adapted to filter the water entering therethrough, and a diaphragm interposed between said water filled portion of said system and the surrounding water, said diaphragm being adapted to transmit rapid changes in pressure of the surrounding water to the fiuid in said system thereby to apply said pressure differential to said movable member.

5. In an underwater ground mine, the combination of a firing mechanism adapted to fire the mine when the mechanism is actuated, a fiuid system having a portion thereof to be filled from the water in which the mine is launched, a duct for admitting water to said water filled portion of said system, water filtering means disposed in said duct and adapted to filter the water entering therein, a diaphragm having one side thereof exposed to the surrounding water and the other side thereof in communication with the water filled portion of said system and adapted to communicate a change in pressure of the surrounding water to the fiuid in said system thereby to cause a flow of the fluid therein proportional to said change in pressure, and means within said system movably responsive to a predetermined fiow of the fluid therein for actuating said firing mechanism.

6. In an underwater ground mine, the combination of a casing, an explosive charge arranged within said casing, an electroresponsive detonator adapted when energized to explode said charge, a circuit including means for energizing said detonator, a normally open switch included in said circuit, hydroresponsive means for controlling said switch and including a fiuid system having a portion thereof adapted to be filled from the surrounding water, a filling duct for admitting water to said system, filtering means disposed in said duct and adapted to filter the water entering the system therethrough, and a diaphragm interposed between said water filled portion of said system and the surrounding water, said diaphragm being adapted to transmit rapid changes in pressure of the surrounding water through the fluid in said system to said hydroresponsive means thereby to close said switch when a predetermined change in said pressure occurs.

7. In a firing mechanism of the class described for an underwater mine, a dished housing adapted to form a first compartment, a second housing forming a second compartment, fiuid communicating means connecting said compartments, said dished housing having a plurality of circularly arranged apertures therein for filling the compartments with water, an annular water filtering device secured to said dished housing in abutting relation with ci said apertures and adapted to filter the water passing therethrough, a diaphragm centrally arranged within said filtering device and sealed to said dished housing, one side of said diaphragm being exposed to the surrounding water and the other side thereof exposed to the fluid in said first compartment, said diaphragm being adapted to communicate sudden changes in external pressure to the fiuid within the compartments, means associated with said diaphragm for limiting the movement thereof in response to excessive pressure applied thereto, and firing means arranged in said second housing and adapted to operate in response to a predetermined fiow of fluid caused by a change in pressure applied to the fluid within said compartments.

8. In an underwater mine of the character disclosed, a fiuid system comprising two fluid filled chambers, said chambers being separated by a fluid tight partition, a movable element in said partition responsive to difierentials in pressure between said chambers, a resilient diaphragm separating the first chamber from the water in which the mine is planted, a fluid communicating opening between said first chamber and the surrounding water, liquid filtering means for said opening adapted to filter the liquid fiowing therethrough, resiliently urged volume decreasing means in the second chamber whereby pressure differentials between said two chambers are equilized by the motion of said movable element and said resiliently urged means, and a mine firing mechanism actuated by said movable element in response to displacement thereof caused by a hydrodynamic pressure change in said water of predetermined amplitude and duration.

9. In an underwater mine of the character disclosed, a fluid system comprising first and second fiuid filled chambers, a fiuid tight partition including a first bellows separating said chambers, a second bellows resiliently urged to expand into said second chamber, a resilient diaphragm separating the first chamber from water surrounding the mine, a fluid communicating opening between said first chamber and the surrounding water for filling said first chamber with water, liquid filtering means for said opening adapted to filter the liquid fiowing therethrough, a mine firing mechanism, a switch adapted to fire said firing mechanism and nonactuated at the normal equilibrium positions of said bellows, and means including said first bellows for actuating said switch upon expansion of the first bellows in response to the differential pressure established between said rst and second chambers by a decrease in water pressure of predetermined amplitude and duration transmitted to said first chamber by said diaphragm and the urged expansion of said second bellows.

References Cited in the file of this patent UNITED STATES PATENTS 2,414,804 Duncan Jan. 28, 1947 FOREIGN PATENTS 557,110 France Ian. 27, 1925 604,038 France T Apr. 28, 1926 

1. IN AN UNDERWATER GROUND MINE, THE COMBINATION OF A CASING, AN EXPLOSIVE CHARGE ARRANGED WITHIN SAID CASING, AN ELECTRORESPONSIVE DETONATOR ADAPTED TO EXPLODE SAID CHARGE, A CIRCUIT INCLUDING MEANS FOR FIRING SAID DETONATOR, AT LEAST ONE SWITCH FOR CONTROLLING SAID CIRCUIT, A MOVABLE MEMBER FOR CONTROLLING SAID SWITCH, A FLUID SYSTEM IN WHICH THE FLUID FLOW THEREIN IS ADAPTED TO CONTROL THE MOVEMENT OF SAID MOVABLE MEMBER IN RESPONSE TO CHANGES IN HYDROSTATIC PRESSURE APPLIED TO SID FLUID, A DUCT FOR FILLING AT LEAST A PORTION OF SAID SYSTEM FROM THE WATER IN WHICH THE MINE IS PLANTED, WATER FILTERING MEANS ARRANGED IN SAID DUCT FOR EXCLUDING FOREIGN MATTER FROM SAID FLUID SYSTEM, AND A DIAPHRAGM INTERPOSED BETWEEN THE SAID 